Morbidity amongst South African Hajj pilgrims in 2023—a retrospective cohort study

South Africans are not accustomed to the dry arid climate and sweltering heat in Saudi Arabia. We conducted a retrospective cohort study to identify the common health conditions pre-Hajj, during the 5 days of Hajj and on return to South Africa from Hajj amongst the 2023 pilgrims. A QR code and a mobile link to a self-administered questionnaire was sent to all 3500 South African pilgrims. Five hundred and seventy-seven pilgrims returned the completed surveys. Mean age of the participants was 48 years (SD 12) with a higher female representation (3:2). Forty eight percent (279) had pre-existing chronic conditions. Forty five percent (259) reported being ill during their stay in the Kingdom, 20% (115) reported having an illness during the main 5 days, whilst 51% (293) reported having an illness within 7 days of returning to South Africa. Only six pilgrims were admitted to hospital after their return home. Respiratory tract linked symptoms were the most frequently reported (95% pre Hajj and 99% post Hajj). Participants who reported having a chronic condition (AOR 1.52 95% CI 1.09–2.11) and engaging in independent exercising prior to Hajj (AOR 1.52–1.07–2.10) were at an increased likelihood of developing an illness within 7 days of returning home. Post travel surveillance swabs to identify potential pathogens that the returning pilgrims are incubating should be explored to guide further interventions.


Data analysis
Statistical analysis was performed using IBM Statistical Software for Data Science (STATA) version 18, (IBM Corp. Armonk, NY).Age was the only continuous variable and was computed as mean ± SD, whilst all other categorical variables were recorded as percentages.Initially a descriptive analysis was conducted.Bivariate analysis was performed to calculate unadjusted odds ratio for all sub-categories for demographic variables.All the baseline variables (age category, gender, smoking status, marital status, health status prior to Hajj, body weight, vaccination status, attendance at a fit for Hajj program, number of kilometres that the person can walk, Hajj package duration and presence or absence of a chronic condition) were included in the model to assess the association between demographic factors, attendance of an exercise program and the development of illness prior to and post Hajj using a value of 0.05.

Results
Table 1 summarizes the demographic characteristics of the participants.Five hundred and seventy-seven pilgrims returned the completed surveys.Forty seven percent (269) of the participants purchased a 3-4-week package, whilst a further 45% (262) purchased a 5-6-week package.The mean age of the participants was 48 years (SD 12) with both males and females having similar age distribution.There was a higher female representation with a sex ratio of 3 females for every two males.Most of the pilgrims assessed their health to be excellent (121, 21%) or good (286, 50%) prior to the Hajj journey.Thirty two percent (184) were overweight and 18 (3%) were obese.Although 33% (189) attended a formal exercise program prior to Hajj, 60% (346) indicated that they exercised prior to Hajj.Thirty three percent (193) were able to walk between 5 and 10 km comfortably, whilst 162, 28%) could walk more than 10 km comfortably.Forty eight percent (279) had one or more chronic condition that they were being treated for (Table 1).
Forty eight percent (279) of the pilgrims reported having been diagnosed with a chronic disease prior to the embarking on Hajj.The eight most co0mmon chronic conditions are displayed in Fig. 1.Hypertension as a single diagnosis (18%) or hypertension with other co-morbidities (21%) were the most common chronic condition.Nine percent of the pilgrims had asthma/emphysema.

Discussion
Fifty one percent (293) of the current cohort of Hajj 2023 pilgrims reported acquiring an illness within 7 days of returning from pilgrimage.Although, a similar incidence (52%) was reported among Australian from Greater Sydney, New South Wales, Hajj travellers aged 18 years or older in 2015 8 , the incidence exceeds the 40% (365/915) reported amongst South African pilgrims attending Hajj in 2017 9 .In contrast to the relatively higher post Hajj illness, 45% of pilgrims (259/577) reported being ill during their stay in the Kingdom, with 30% (168/577) experiencing a single illness during their stay, which was lower than the 65.1% (596/916) reported amongst the 2017 South African Hajj cohort 9 and the 74% amongst the 2015 Australian Hajj cohort 8 .Globally the high frequency of respiratory infections during the Hajj and post Hajj transmission is well described 10 , and respiratory tract infections are the most frequently reported disease among South African pilgrims returning from the Hajj 11 .In our study 95% and 99% of the ill pilgrims during and post Haj reported respiratory symptoms.This is much higher than the 70% pre-Hajj and 80% post Hajj reported for the 2017 South African Hajj cohort 9 , however the pre Hajj incidence is similar to the Malaysian study that reported a 95.2% incidence of respiratory symptoms amongst pilgrims during their stay in Saudi Arabia 12 .Previous estimates indicate that 33% of Hajj pilgrims develop a respiratory infection 13 and in our study 43% and 50% of the pilgrims reported respiratory tract symptoms prior to and post Hajj respectively.www.nature.com/scientificreports/Age, gender, marital status, baseline weight status and perception of health status, smoking vaccination status, duration of Hajj package, participation at a fitness for Hajj 12 week program prior to Hajj and distance that a person was able to walk did not show any statistical association with developing an illness on return from Hajj.Pilgrims with chronic conditions were significantly more likely to develop a post Hajj illness (AOR 1.52 95% CI 1.09-2.11).Previous studies have indicated that hypertension and diabetes are associated with increased risk of respiratory tract infections 14,15 .In the current study 47% of the pilgrims had a chronic disease with hypertension with or without co-morbidities (39%) being the most common chronic disease followed by diabetes with/ without co-morbidities (14%).
Vaccination uptake was high amongst the pilgrim with 85% (490) receiving yellow fever, quadrivalent meningococcal vaccine and 44% receiving the Influenza vaccine.In addition, 9% of the pilgrims were vaccinated against pneumococcal disease).Although vaccinations may have reduced the severity of the illness, it did not confer significant protection against developing a respiratory illness post Hajj.
The high incidence of respiratory illnesses during the pilgrims stay in Saudi Arabia can be attributed to crowding, fatigue and the extreme climatic conditions that facilitate droplet and aerosol spread of particulates 16 .We postulate that international travel and seasonality have additionally contributed to the high incidence of respiratory tract infections post Hajj.Most pilgrims are exhausted post the 5-day rituals and many return immediately home.Exhaustion compounded by the long duration of travel back to South Africa that includes a bus trip from Mecca to Jeddah, extended waiting in a crowded setting at the Hajj terminal, and exposure to re-circulated air from other pilgrims that maybe incubating infections can increased risk of transmission.Secondly, the Hajj in Saudi Arabia was during the peak summer season and on return the pilgrims were exposed to peak winter weather in South Africa and the environmental conditions may have increased the incidence of respiratory tract episodes and symptoms 17 .
Our study indicates that pilgrims who did independent exercise prior to Hajj were more likely to develop a respiratory infection.We did not assess whether the independent exercise performed prior to Hajj were moderate or strenuous.Athletes and individuals involved in heavy training programmes and/or prolonged bouts of exercise appear to have an increased risk of contracting upper respiratory tract infections 18 .Previous studies have shown that endurance athletes who experience significant stress and sleep deprivation Increase the risk of infection 19 .The external factors such as duration of travel, extensive pathogen exposure, sleep disruption, journey related stress, and change in diet and nutritional habits during the Hajj journey may have compounded the effect on the immune system and increased their risk for upper respiratory tract infection 20 .
Smoking was a surprisingly protective factor against reporting an illness immediately post Hajj.These findings maybe due to the lower prevalence of pilgrims reporting to be smokers rather than a postulated 'smoker's paradox 21 .Research has shown that compared with non-smokers, currently smoking was associated with higher rates of severe infectious respiratory diseases such as pneumonia, other acute lower respiratory tract infection and influenza 22 .

Study limitations
Although, we reached the minimum sample size required, out sample represents only 17% of the total pilgrims and the findings may not be generalizable.We note that majority of the participants were from the Western Province and Gauteng which are the two Provinces that experience harsher winters and therefore inflating the incidence of respiratory tract infections.Most of the respondents were early to middle aged adults and therefore it is likely that morbidity is under-represented.Furthermore, recall bias may have affected the participants reporting of symptoms that may have occurred prior to, during and after Hajj and resulted in an under-estimate of the true prevalence of symptoms presented in this study.

Conclusion
Majority of South African Hajj pilgrims in 2023 experienced respiratory related illness within 7 days of their return.Pilgrims with pre-existing chronic diseases of lifestyle were at an increased risk of developing an illness on return from the pilgrimage.Vaccinations against Influenza and pneumococcal disease may have decreased severity but did not decrease the incidence.It is important that the consistent observation of non-pharmaceutical interventions such as wearing of masks in crowded environments, frequent hand washing and social distancing is emphasised.In addition, it maybe necessary to conduct post travel surveillance swabs to identify potential pathogens that the returning pilgrims are incubating.These findings may direct appropriate antibiotic prescription and recommendation on future travel vaccines for Hajj.

Figure 2 .
Figure 2. Proportion of pilgrims reporting having an illness pre-during and post Hajj-2023.

Table 1 .
Frequency distribution of the demographic profile of the participants.

Table 2 .
Univariate bi-variate and multi-variate analysis of demographic profile of Hajj 2023 pilgrims and developing an illness.Significant values are in bold.*p < 0.05.